Xue Li, Guo Ruya, Huang Fengchun, Qi Wuzhen, Liu Yuanjie, Cai Gaozhe, Lin Jianhan
Key Laboratory of Agricultural Information Acquisition Technology, Ministry of Agriculture and Rural Affairs, China Agricultural University, Beijing, 100083, China.
Key Laboratory of Modern Precision Agriculture System Integration Research, Ministry of Education, China Agricultural University, Beijing, 100083, China.
Biosens Bioelectron. 2021 Feb 1;173:112800. doi: 10.1016/j.bios.2020.112800. Epub 2020 Nov 6.
Screening of pathogenic bacteria in foods is an effective way to prevent foodborne diseases. In this study, an impedance biosensor was developed for rapid and sensitive detection of Salmonella typhimurium using multiple magnetic nanobead (MNB) nets in a ring channel for continuous-flow separation of target bacteria from 10 mL of sample, manganese dioxide nanoflowers (MnO NFs) for efficient amplification of biological signal, and an interdigitated microelectrode for sensitive measurement of impedance change. First, the MNBs modified with capture antibodies were vortically injected from outer periphery of this ring channel to form multiple ring MNB nets at specific locations with high gradient magnetic fields. Then, the bacterial sample was continuous-flow injected, resulting in specific capture of target bacteria onto the nets, and the MnO NFs modified with detection antibodies were injected to form MNB-bacteria-MnO NF complexes. After the complexes were washed with deionized water to remove excessive nanoflowers and residual ions, HO with poor conductivity was injected to reduce MnO NFs to conductive Mn at neutral medium, leading to impedance decrease. Finally, impedance change was measured using the microelectrode for quantitative determination of Salmonella. This biosensor was able to separate ~60% of Salmonella from 10 mL of bacterial sample and detect Salmonella with a linear range of 3.0 × 10 to 3.0 × 10 CFU/mL in 1.5 h with lower detection limit of 19 CFU/mL. This biosensor might be further improved with higher sensitivity using a larger volume (100 mL or more) for routine screening of foodborne bacteria without bacterial pre-culture.
食品中病原菌的筛查是预防食源性疾病的有效方法。在本研究中，开发了一种阻抗生物传感器，用于快速、灵敏地检测鼠伤寒沙门氏菌。该传感器利用环形通道中的多个磁性纳米珠（MNB）网对目标细菌进行连续流分离，从10 mL样品中分离出目标细菌；利用二氧化锰纳米花（MnO NFs）高效放大生物信号；利用叉指式微电极灵敏测量阻抗变化。首先，将用捕获抗体修饰的MNB从该环形通道的外周涡旋注入，在具有高梯度磁场的特定位置形成多个环形MNB网。然后，连续流注入细菌样品，使目标细菌特异性捕获到网上，再注入用检测抗体修饰的MnO NFs，形成MNB-细菌-MnO NF复合物。用去离子水洗涤复合物以去除过量的纳米花和残留离子后，注入导电性差的HO在中性介质中将MnO NFs还原为导电的Mn，导致阻抗降低。最后，使用微电极测量阻抗变化以定量测定沙门氏菌。该生物传感器能够从10 mL细菌样品中分离出约60%的沙门氏菌，并在1.5小时内检测沙门氏菌，线性范围为3.0×10至3.0×10 CFU/mL，检测下限为19 CFU/mL。该生物传感器可通过使用更大体积（100 mL或更多）进行进一步改进，以提高灵敏度，用于食源性细菌的常规筛查，无需细菌预培养。
